The Government of Bhutan is a constitutional monarchy. Between, 1907 to 1950s Bhutan however was an absolute monarchy. The peaceful march to democracy has been a steady one. The King of Bhutan is head of state. Executive power is exercised by the Lhengye Zhungtshog, or council of ministers, headed by the Prime Minister. Legislative power is vested in the bicameral Parliament, both the upper National Council and the lower National Assembly. In 2008, Bhutan adopted its first modern Constitution, codifying the institutions of government and the legal framework for a democratic multi-party system. King is head of state and Prime Minister is head of the government.